1) The document discusses how to boot a ShareTech mail server from a USB device such as a flash drive or external hard drive in an emergency situation when the server's original hard drive fails.
2) It explains that the USB device must have equal or more space than the original hard drive. It also notes that booting from USB is only a temporary solution and the server should be repaired by contacting support.
3) The document provides steps for connecting to the server via console cable and putty to boot from a USB device, selecting options during restart to boot from the USB, and notes when the server startup is complete.